The very definition of faith is that one who has strong belief, firm belief on the words of the Supreme Personality of Godhead, Sri Krishna.
Meaning, one who has full faith that whatever Krsna is speaking in Bhagavad Gita, that is the absolute truth, nothing but absolute truth. This is called Śrāddha.
“Sraddhā’-śabde—viśvāsa kahe sudṛḍha niścaya
kṛṣṇe bhakti kaile sarva-karma kṛta haya.”
Krsna Das Kaviraj Goswami says-
‘śraddhā’-śabde—viśvāsa kahe’
‘śabde—viśvāsa’, meaning in the words of Krsna , one has full faith and what are His words? Bhagavad Gita, Bhagavatam and wherever He says, Bhagavan uvaca , Krsna, Visnu uvaca or Rama uvaca. These are His words.
“Niścaya”, meaning strong determination in believing that whatever Krsna says is the absolute truth, nothing but absolute truth. In other words, our scriptures are absolute truth and there is no question of any doubt, no doubt.

In a question answer session, Prabhupada said, “Any doubts? and one Indian Gentleman said, “Yes, How can I understand that Bheem used to eat so many pounds of Ladoos. It is not true.” And Prabhupada became like a red hot tiger, lion kind of face, Prabhupada was very furious and He shouted, “You rascal you don’t have faith in Scriptures, keep quiet.” You don’t have any faith that whatever scriptures say is absolute truth.
So this is faith, it means whatever scriptures say is absolute truth, no question, it is no exaggeration.
When Krsna says in Bhagavad Gita, anything and everything that is the law, absolute truth. A King can do no wrong. Krsna can do no wrong, Krsna is the king of all the kings. Krsna is the Supreme Personality of Godhead and whatever He says, whatever He does, He cannot do wrong , this is faith.

He is right under all circumstances. Whatever Krsna does is absolute truth, it looks in a superficial, mundane way that He is wrong, that He is instructing Arjuna to kill Karna when He is off the chariot, He is trying to take his chariot out of dirt, at that time Krsna orders him. But people may find faults. Like Lord Ramchandra killing Baali, people find faults with Lord Ramchandra. But they don’t see the past why Lord did this. So this is no faith. Whatever Lord does is absolute, it is the truth and this kind of staunch faith in Lord’s words, actions, pastimes, this is called faith.
‘Sraddhā’-śabde—viśvāsa kahe sudṛḍha niścaya’ and if you’ve this staunch faith then what happens ‘kṛṣṇe bhakti kaile sarva-karma kṛta haya’. That by accepting Krishna’s words, Prabhupada says one can achieve all perfection. You can achieve all perfection. This is faith. This faith should be there, staunch faith in our heart.